1. Field of the Invention
The present invention relates to a filler-containing resin composition that con be very readily for being formed by stretching, and that is advantageously usable for the formation of thin gas-permeable formed bodies which can exhibit excellent elastic recovery, strength and feeling, and very excellent gas-permeability when used as sanitary materials, or the formation of thin gas-permeable formed bodies which involve no smoking or roll staining when worked and are able to exhibit excellent gas-permeability, strength and weathering resistance when applied to outdoor uses. The present invention also relates to an stretched film formed by using such a filler-containing resin composition.
2Description of the Related Art
A known technique lot forming a gas-permeable film having through voids extending continuously through the thickness thereof comprises stretching, either uniaxially or biaxially, an unstretched film or the like formed of a composition containing an olefin-based resin and an inorganic filler. An stretched film formed by using such a composition is applied to various uses. For instance, the stretched film is used as a sanitary material for disposable paper diapers, etc., or as a material for an outdoor-use gas-permeable sheet (such as a protective sheet laid on the inside of roof tiles or outer walls of wooden constructions for the purpose of waterproofing and other weathering performance, or a protective sheet applied at the root, etc., of fruit trees or the like for the purpose of heat insulation, etc).
However, it has been difficult to form a conventional resin composition into a thin formed body because the composition does not have sufficient capability of being formed by orientation, nor does it have sufficient strength.
Although it has been desired that a resin composition be formed into thin forms for the purpose of saving resources, rationalizing production, etc., conventional resin compositions have not been quite able to meet such demands.
A film for disposable paper diapers or the like is required to have certain properties in addition to an adequately small thickness, which include good gas (typically, air or water vapor) permeability, and good hand or feeling. In recent years, it has been required that this kind of product have good fitting properties. In order to assure proper fit, a film used in the product must have elastic recovery.
Paper diapers, which are for absorbing liquids, must have good gas-permeability in order to avoid becoming stuffy. Products which may become stuffy are not welcomed by consumers. Further, consumers have recently come to demand products of higher quality than ever, and paper diapers are desirably capable of being closely fitted on the body as pants-type paper diapers are. In order to assure proper fit of paper diapers, a material capable of freely stretching and contracting (i.e., capable of exhibiting elastic recovery) is required. In addition, such a material must also have better feeling than ever.
Conventional gas-permeable sheets or films for outdoor use have insufficient properties with respect to gas (typically, air) permeability, strength, and the capability of being formed at an adequately small thickness. Furthermore, the conventional product has such insufficient weathering resistance that, when used in summer, the film or sheet deteriorates within one or two months, becoming totally useless. In order to improve weathering performance, the conventional practice includes adding agents for imparting weathering resistance (e.g., an ultraviolet screener, and a light stabilizer). However, this method involves many disadvantages. For instance, smoking may occur during forming, or the chill rolls may be contaminated with bled substances. Further, the thus obtained product may have such poor printability that ink in printed portions may easily come off, or the product may be vulnerable to contamination with dust, etc. Thus, conventional products have insufficient properties to be used as gas-permeable films for outdoor uses.